Sorry for the delay… but there is a reason. 
I did not try the Arduino IDE on this machine. I don’t know - BUT I think I know the reason now. I bought a new PC and started all over from scratch. Everything with default settings.
This USB-port has troubled me on many other occasions - I have both a USB-port extender and the native USB-port. They react a bit differently and the best is the native build in port. I am a bit nervous to use the native because I have experienced damaged ports (because of all my experiments with electronics) - so I prefer to use an extender.
I installed Arduino on the new machine - it worked.
Then I tried PlatformIO - it worked. 
So I am happy and can go on experimenting - it’s so much fun…
Thank you for your kind support - I have donated a small amount to keep you up and running.